aquifex thermotoga

1. Bacterial Diversity
Presentation
Prepared and Presented by
Deepika Rana
1601
M.Sc. Microbiology (I)
MDU,Rohtak

2. Thermophilic microbes are found in both the bacterial and archael
domains, but to date, all hyperthermophilic prokaryotes(those with
optimum growth temperature above 85°C) belong to the Archae.
The phylum Aquificiae and Thermotoga are two best examples of
bacterial thermophiles.

3. •A thermophile is an organism – a tyoe of extremophile- that
thrives at relatively high temperature, between41 and 122°C(106
and 252°F). E.g.,Sulfolobus acidocaldarius, Thermus aquaticus.
•Thermophilic eubacteria are suggested to have been amongst the
earliest bacteria.
•Thermophiles are found in various geothermally heated regions
of the Earth, such as hot springs like those of Yellowstone
National Park and deep sea hydrothermal vents as well as
decaying plant matter, such as peat, bogs and compost.
•Thermophiles contain enzymes that can function at high
temperature.
•Some of these enzymes are used in molecular biology, and in
washing agents.
•The G+C content levels was correlated with the temperature
range condition.

4. Scientific Classification
• Domain: Bacteria
• Phylum: Aquificae
• Class: Aquificae
• Order: Aquificales
• Family: Aquificaceae
• Genus: Aquifex
• Species: A. Aeolicus
A. pyrophilus
Aquificae habitat
White flocculent mats in and around the
extremely gassy, high-temperature (>100°C,
212°F) white smokers at Champagne Vent.

5. • They are true bacteria as opposed to
the other inhabitants of extreme
environments, the Archaea.
• Aquifex pyrophilus is a gram-negative,
microaerophilic rods.
• It is non-spore forming.
• They are generally 2.0-6.0µm in length
and have a diameter of 0.4-0.5µm.
• Like A. pyrophilus, A. aeolicus is motile
and possesses monopolar polytrichous
flagella. More than25 genes encoding
proteins involved in flagellar structure
and biosynthesis have been identified
in A.aeolicus.
Aquifex pyrophilus (ultrathin section).

6. • As autotrophic organisms, Aquifex fir carbon di-
oxide from the environment to get the carbon
they need.
• They are chemolithotrophic which means that
they draw energy for biosynthesis from inorganic
chemical sources.
• The enzymes this organism uses for aerobic
respiration are similar to those present in other
aerobic bacteria.
• Non-N-methylated APT lipids can be observed as
a common phospholipids head group in Aquifex.

7. As an autotroph, A. aeolicus obtains all necessary carbon by fixing CO2 from the
environment.
The reductive (reverse) TCA cycle fixes two molecules of CO2 to form acetyl-
coenzyme A (acetyl-CoA) and other biosynthetic intermediates.
The A. aeolicus genome contains genes encoding malate dehydrogenase,
fumarate hydratase, fumarate reductase, succinate-CoA ligase, ferredoxin
oxidoreductase, isocitrate dehydrogenase, aconitase and citrate synthase, which
together could constitute the TCA pathway.
The TCA cycle is vital as it provides the substrates of many biosynthetic
pathways.

8. Growing autotrophically, A. aeolicus must synthesize pentose and hexose
monosaccharides from products of the reductive TCA cycle.
Pyruvate produced by pyruvate ferredoxin oxidoreductase or by pyruvate carboxylase
(oxaloacetate decarboxylase) may enter the Embden–Meyerhof–Parnas pathway of
glycolysis and gluconeogenesis.
Genes encoding fructose-1,6-bisphosphatase, an essential gluconeogenic enzyme
in E. coli, have not been identified in the genomes of the autotrophs A. aeolicus or,
suggesting that an unidentified pathway may exist.
The A. aeolicus genome also encodes enzymes of the pentose-phosphate
pathway and enzymes for glycogen synthesis and catabolism.
The main enzymes involved in Entner- Duodroff Pathway are also absent.

9. •Aquifex species are able to grow by using oxygen
concentrations as low as 7.5 p.p.m.
•The enzymes for oxygen respiration are similar to those of
other bacteria: ubiquinol cytochromec oxidoreductase
(bc 1 complex), cytochrome c (three different genes) and
cytochrome c oxidase .
•The physiological role of most of these oxidoreductases is
unknown or ambiguous, but two deserve comment. There is a
putative nitrate reductase in the genome, although A.
aeolicus has not been observed to perform NO3
- respiration,
unlike the closely related A. pyrophilus.

10. •A. aeolicus grows optimally under microaerophilic conditions and
consequently possesses various protective enzymes to counter
reactive oxygen species, particularly superoxide and peroxide.
•The genome contains three genes encoding superoxide dismutases.
•No catalase genes were identified.
•There are several genes in the genome that might encode proteins that
catalyze the detoxification of H2O 2, including cytochrome c peroxidase,
thiol peroxidase, and two alkyl hydroperoxide reductase genes.
•All of these enzymes require an exogenous reductant and therefore do not
evolve O2. However, treatment of A. pyrophilus or A. aeolicus biomass with
H2O2 results in the rapid evolution of gas bubbles.

11. • Aquifex are thermophilic and often grow underwater
volcanoes, thermal ocean vents, sulfur pools or hot springs.
• It needs oxygen to carry on its metabolic machinery, but it can
function in relatively low levels of oxygen (A. pyrophilus can
grow in levels of oxygen as low as 7.5 ppm).
• A.aeolicus and A.pyrophilus can grow at 95°C; they are one of
the most thermophilic bacteria known.
• A.aeolicus was first obtained by R.Huber and K.F. Stetter at the
Aeolic island (North of Sicily, Italy) whereas A.pyrophilus was
obtained at the Kolbensey Ridge, North of Iceland.

12. Approximately 2 meters downstream of the spring pictured to the right. Pink
microbial filaments containing Aquifex and Thermotoga were found in this channel.
The tempurature was measured to be 83 degrees Celsius and the pH was found to be
8. From the Lunar and Planetary Institute.

13. • Hyperthermophilic bacteria such as Aquifex are
important for industrial purposes.
• Its genes can be used in a variety of
biotechnological applications.

14. Scientific Classification
Domain: Bacteria
Phylum: Thermotogae
Order: Thermotogales
Family: Thermotogaceae
Genus: Thermotoga
Species: T.elfii
T.hypognae
T.lettingae
T.maritima
T.napthophila
T.neapolitana
T.petrophila
T.subterranea

15. • Thermotoga maritima is a non-sporulating, rod shaped, gram
negative bacterium.
• When viewed under a microscope, it can be seen to encased in
a sheath-like envelope which resembles a toga, hence the
"toga" in its name.
• The members of the phylum stain Gram-negative as they
possess a thin peptidoglycan in between two lipid bilayers,
both peculiar. The peptidoglycan is unusual as the crosslink is
not only meso-diaminopimelate as occurs in Proteobacteria,
but D-lysine.
• The species are anaerobes with varying degrees of oxygen
tolerance. They are capable of reducing elemental sulphur (S0)
to hydrogen sulphide, which in turn can be used.

16. • The CG (cytosine-guanine) content of T. maritima is
46.2%; most thermophiles in fact have high CG content; this
has led to the speculation that CG content may be a non-
essential consequence to thermophily and not the driver
towards thermophily.
Outline of a Thermotoga maritima section
showing the "toga".

17. • As an anaerobic
fermentative chemoorganotrophic organism, T.
maritima catabolizes sugars and polymers and
produces carbon dioxide and hydrogen gas as by-
products of fermentation.
• T. maritima is also capable of metabolizing cellulose
as well as xylan, yielding H2 that could potentially be
utilized as an alternative energy source to fossil
fuels.
• Additionally, this species of bacteria is able to
reduce Fe(III) to produce energy using anaerobic
respiration.
• Collectively, these attributes indicate that T.
maritima has become resourceful and capable of
metabolizing a host of substances in order to carry
out its life processes.

18. • First discovered in the sediment of a marine
geothermal area near Volcano, Italy, Thermotoga
maritima resides in hot springs as well as
hydrothermal vents.
• Thermotoga species have been isolated from
geothermally heated environments across the globe,
including oil reservoirs, submarine hot springs, and
continental sulfur springs
• The ideal environment for the organism is a water
temperature of 80 °C (176 °F), though it is capable of
growing in waters of 55–90 °C (131–194 °F).
• Thermotoga maritima is the only bacterium known to
grow at this high a temperature; the only other
organisms known to live in environments this extreme
are members of the domain Archaea.
• The hyperthermophilic abilities of T. maritima, along
with its deep lineage, suggests that it is potentially a
very ancient organism.
Yellowstone National Park

19. • T. maritima’s xylanolytic abilities have attracted interest for food,
paper, and biofuel-related applications.
• Xylooligosaccharides resulting from xylan degradation have been
shown to increase the numbers of beneficial gut bacteria, such
as Bifidobacterium species.
• Their ability to degrade a wide range of simple and complex
carbohydrates, produce fermentative hydrogen at high yield, and
catalyze a variety of high-temperature reactions has been the basis
for numerous biotechnological applications.
• These bacteria are also viewed as model systems for studying
adaptation to high temperature and microbial evolution, as they
present a challenge to conventional classification.
• A number of genome sequences for Thermotoga species have
become available in the past few years , offering additional insights
into the biology of these interesting bacteria and suggesting
biotechnological opportunities.

20. 1. Prescott’s Microbiology 7th edition Wiley et al
2. www.els.net
3. mcmanuslab.ucsf.edu
4. Britannica
5. Google images
6. Wikipedia